package com.hmdp.utils;


import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;

import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import java.sql.Time;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

@Slf4j
@Component
public class CatcheClient {

    private final StringRedisTemplate stringRedisTemplate;

    public CatcheClient(StringRedisTemplate stringRedisTemplate) {
        this.stringRedisTemplate = stringRedisTemplate;
    }

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(value),time,unit);
    }
    //设置逻辑过期时间
    public void setWithLogicalExpire(String key, Object value, Long time, TimeUnit unit){
        //设置逻辑过期
        RedisData redisData=new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //写入Redis
        stringRedisTemplate.opsForValue().set(key, JSONUtil.toJsonStr(redisData));
    }

    //缓存穿透
    public <R,ID> R queryWithPassThrough(
            String keyPrefix, ID id, Class<R> type, Function<ID,R> dbFallback, Long time, TimeUnit unit){
        String key =keyPrefix + id;
        //1.从redis查询商铺缓存 商品数据使用Redis里面的string缓存的
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(json)){  //"" "/t" null 返回false "abc"返回true
            //3.存在，直接返回
            //因为shopJson是json格式的所以要转换为字符串
            return JSONUtil.toBean(json, type);
        }
        if (json!=null){
            return null;
        }
        //4.不存在 ，根据id查询数据库
        R r = dbFallback.apply(id);
        //5.判断商品是否存在
        if (r==null){
            stringRedisTemplate.opsForValue().set(key,"",RedisConstants.CACHE_NULL_TTL,TimeUnit.MINUTES);
            //6.不存在直接返回
            return null;
        }
        //7.存在写入redis
      this.set(key,r,time,unit);
        // 8.返回
        return r;
    }

    //缓存击穿
    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    public <R,ID> R queryWithLogicalExpire(
            String keyPrefix,ID id,Class<R> type,Function<ID,R>dbFallback,Long time,TimeUnit unit){
        String key = keyPrefix+ id;
        //1.从redis查询商铺缓存 商品数据使用Redis里面的string缓存的
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否命中
        if (StrUtil.isBlank(json)){  //"" "/t" null 返回false "abc"返回true
            //3.未命中直接返回
            return null;
        }
        //4.命中，需要把json反序列化对象（需要把redis里面的数据取出来）
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        JSONObject data = (JSONObject)redisData.getData();
        R r = JSONUtil.toBean(data, type);
        LocalDateTime expireTime = redisData.getExpireTime();
        //5.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //5.1未过期 直接返回店铺信息
            return r;
        }
        //6 已过期 需要缓存重建
        //6.1获取互斥锁
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        //6.2判断是否获取互斥锁成功
        if (isLock){
            //6.3成功 开启独立线程 实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    //缓存重建
                    //数据库查询
                    R r1 = dbFallback.apply(id);
                    //写入redis
                    this.setWithLogicalExpire(key,r1,time,unit);
                } catch (Exception e) {
                    throw new RuntimeException();
                }finally {
                    unlock(lockKey);
                }
            });
        }
        //6.4返回过期商铺信息

        return r;
    }
    //加上锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //删除锁
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }



}
